Cautioning that more research is needed before these early findings can be fully confirmed—HPV researchers elsewhere say it’s not been proven that other regions are witnessing the same patterns as those shown in this new study—the North Carolina research team investigated the potential interplay between the vaccine and different types of HPV diagnosed among the 572 Durham County, N.C. women who enrolled in the study.

“It was a single population from a single clinic. All of these women came from a small geographic area, and we know that women tend to have sex partners in the area where they live,” Dr. Rebecca Perkins, a Boston University Medical Center researcher of HPV in poor and under-served communities and gynecologist, told the Grio. “It’s hard to [apply] this to any other states or, for that matter, to a health center outside of Duke.”

Of the 572 women, aged 18 and older, 280 of them were black and 292 were non-Hispanic whites.

In reviewing cervical pap smears taken since 2010, these researchers found that more than half of the women had changes associated with developing cervical cancer — 239 in the early-stage and 88 in the advanced stage. And many of the women — 73 percent — were infected with more than one type of HPV. There are 40 subtypes in total.

The HPV vaccine prevents infection from subtypes 16 and 18. Combined, those two account for 70 percent of cervical cancers, these researchers wrote.

In the study out today, the white women with early and advanced pre-cancerous abnormalities tested positive for the HPV 16 and HPV 18 subtypes. But in black women, neither HPV 16 nor HPV 18 were commonly found.

Instead, the most commonly detected subtypes during the early precancerous stage were HPV subtypes 33, 35, 58 and 68. HPV subtypes 31, 35, 45, 56, 58, 66 and 68 were the most commonly detected in black women with advanced-stage pre-cancerous abnormalities.

“Compared with white women, we saw that African-American women had about half as many infections with HPV 16 and 18, the subtypes that are covered by HPV vaccines,” said Adriana Vidal, Ph.D., an assistant professor of obstetrics and gynecology at Duke and the study’s lead investigator, according to a press release. “Since African-American women don’t seem to be getting the same subtypes of HPV with the same frequency, the vaccines aren’t helping all women equally.”

This study has not been approved for publication in a medical journal, though the authors have applied to have their work published, Duke Medical Center spokeswoman Rachel Harrison told the Grio via email.

Morehouse School of Medicine’s Dr. Hedwige DiDi Saint-Louis said she hopes these preliminary findings lead no one to reflexively believe the vaccine is either ineffective or unnecessary. She will continue to encourage her patients to get vaccinated, she said.

In 2006, the U.S. Food and Drug Administration approved the HPV vaccine for prevention of cervical cancer, a disease that kills a greater percentage of black women than white women. Sold under the brand names of Gardasil or Cervarix, the drug has fueled debate, largely because it’s recommended for boys and girls to begin getting the series of three vaccination shots starting when they are about 11 or 12 years old.

Although a new HPV vaccine targeting HPV subtypes 16, 18 and seven other types is currently being tested in clinical trials, the Duke and University of North Carolina researchers noted that, even if approved for use, it may not address the challenges detailed in their research.

Similarly, Saint-Louis added that this study spotlights the lingering question of whether pharmaceutical firms, among others, are doing enough to ensure that their clinical trials include all racial and ethnic groups. Coupled with that is a lingering reluctance of many non-whites to sign up for trials that do exist.

“With most of these clinical trials, there’s an issue with recruiting African-Americans and other minority populations,” Saint-Louis said. “ … Always, we need to look at genetic differences in disease and treatment. The goal in clinical trials should be to get as wide a circle of participants as possible so that the trials represent the population at large. Then, you can confidently generalize about what the findings truly mean.”

Taking race-based genetics into account should be a front-end priority for drug-makers aiming to make effective medicines, Saint-Louis said. “If it isn’t, that greatly increases the likelihood that [pharmacology] is going to miss something that makes a difference for minority groups.”

Patricio Meneses, Ph.D., an epidemiologist and HPV researcher at Fordham University in New York City, said drug-makers might be better advised—and the public better served—by developing a more powerful “second-generation vaccine that actually attacks the biology of virus … after it gets inside the body’s cells.”

The current vaccines don’t go that far, he added. They work by keeping the many subtypes of viruses from attaching to the outside of cells.